1. Technical Field
The present invention relates to a medium feeding device which feeds a medium and an image reading apparatus which includes the medium feeding device.
2. Related Art
There is a case where a scanner which is an example of an image reading apparatus includes an automatic document feeder (also referred to as an auto document feeder (ADF)) as a medium feeding device and thus is configured to automatically feed and read a plurality of documents.
The medium feeding device includes a feeding roller which feeds a medium and a separating roller which nips and separates the medium between the feeding roller and the separating roller.
In a case where such a scanner is continuously used, replacement or cleaning of the feeding roller and the separating roller may be performed due to abrasion of each roller surface and adhesion of paper dust generated from a medium to be fed.
For example, JP-A-2014-60494 discloses an image forming apparatus (scanner) which includes a sheet transport device as the medium feeding device and can exchange the feeding roller and the separating roller of the sheet transport device.
In JP-A-2014-60494, the housing including the scanner is divided into an upper portion unit (cover portion 11b) and a lower portion unit (main body portion 11a), and in a case where maintenance of the medium feeding device or clearing of a paper jam is performed, the upper portion unit is configured to be openable and closable with respect to the lower portion unit.
There is a case where the feeding roller or the separating roller includes a roller cover which exposes a portion of the roller and constitutes a portion of a transport path of the medium.
For example, in FIG. 5 of Japanese Patent No. 5663340, a roller cover which exposes a portion of a paper feeding roller 121 (the reference numeral is not illustrated in FIG. 5 of Japanese Patent No. 5663340, see FIG. 2), constitutes the transport path of the medium and is formed flush with a lower side guide 107a is disclosed.
In addition, in FIG. 9 of JP-A-2010-30772, a medium reading apparatus in which the roller cover 15 is also provided for a retard roller 7 as the separating roller is disclosed.
In JP-A-2010-30772, the roller cover 15 is rotatably supported about a point shaft 151 as a point with respect to an upper portion guide 18 on which the retard roller 7 is provided.
In a case where replacement or maintenance of the retard roller 7 is performed, the roller cover 15 is in an open state.
In a configuration in which the upper portion unit opens and closes with respect to the lower portion unit, in a case where the roller cover for the feeding roller is provided so as to open and close by rotating with respect to the lower portion unit on which with the feeding roller is provided, since a hinge portion of the roller cover may be damaged if the upper portion unit is closed in a state in which the roller cover is open, it is necessary for an opening angle of the roller cover to be an angle (for example, an acute angle) in which the roller cover naturally closes even if the upper portion unit is erroneously closed in a state in which the roller cover is open.
If the opening angle of the roller cover is narrow, maintenance work such as replacement or cleaning of the roller becomes difficult.
In addition, in the case where the roller cover is provided to not only the feeding roller but also the separating roller, it is necessary to prevent mutual interference in a case where the respective roller cover is opened at the same time and thus the opening angle of the roller cover is further narrowed.
Further, when the upper portion unit is erroneously closed in a case where the roller covers of both the feeding roller and the separating roller are in the open state, the roller cover and the upper portion unit or the lower portion unit to which the roller cover is attached may be damaged as a result of the two roller covers being in contact with each other. In addition, since the roller cover constitutes a medium transport surface, the transport surface may be scratched.